Jupiter, Io, Europa, and Ganymede taken by the Galileo spacecraft in 1996, Kallisto by Voyager 2 in 1979
Image: NASA
In April 2023, the European space probe JUICE will be launched to the moons of Jupiter. These hold some secrets – and could be hometowns for alien life.
Ahen Galileo Galilei discovered four moons orbiting Jupiter in 1610, it shook an entire worldview. And in the centuries that followed, the Jupiter system never stopped surprising. Observations by the passing probes Pioneer 10 and 11, Voyager 1 and 2 and Ulysses have provided for the first time more detailed information about the nature of the moons Io, Europa, Ganymede and Callisto. And when the Galileo probe reached Jupiter in 1995, perhaps the most intriguing feature of the three outer Galilean moons came to light: oceans exist beneath their icy surfaces, heated by tidal forces and radioactive decay. Liquid water, along with organic chemistry, sufficient energy, and stable conditions are, as far as we know, the basic ingredients for life – so could such things have originated in the Jovian system?
The European Space Agency ESA will pursue this question in the first major mission of its “Cosmic Vision 2015 – 2025”. The “JUpiter ICy moon Explorer”, JUICE for short, will study Ganymede in particular with ten different scientific instruments and swing into orbit around it. On the way, JUICE will fly close to Europa and Callisto several times and also collect information about Io and the smaller moons from a distance. The mission is scheduled to start in April 2023. But the solar system is big: Unfortunately, it will still be 2031 before JUICE reaches Jupiter – so there are still a few years left to dream of distant and mysterious oceans.